Specify the correct coating
All constructions – small as well as large - are exposed to changing climate impact and corrosion, shortening their service life. The velocity of degradation depends on the environment to which the construction is exposed.
It is crucial to determine whether the surroundings constitute an indoor office climate, a moist factory building for e.g. foods, a hill in the countryside or at sea.
Paint and galvanization are widely used to protect the steel surface against corrosion attacks. The selected paint system and how the coating process progresses are very important if the construction is to be efficiently protected, for many years.
You have to choose which requirements to state in the specification. If the requirements are not sufficient, it will have consequences for the construction’s service life.
If they are too demanding – compared to what is necessary – it makes the coating unnecessarily more expensive and difficult to execute.
You will have to consider:
- Requirements according to standards such as NORSOK M-501, ISO 12944, etc.
- Requirements for surface quality of steel – the degree of degradation that can be accepted before pre-treatment and coating
- Special requirements for steel type as to silicon content and material thickness to achieve the required zinc layer thickness at hot-dip galvanizing
- Which degree of pre-treatment must the steel have as regards welding and edges?
- After blast cleaning, what grade of cleanness is necessary for good adherence?
- How much salt is acceptable on the steel surface?
- What is the corrosion category?
- Which type of paint system should be chosen?
- Is the proposal from the coating company well suited for its purpose, and what are its strengths and weaknesses? Which degree of reporting and documentation should you require from the coating company?
- Which tests/inspections should be performed in the process as well as afterwards?
- How should the tests/inspections be performed? Internally by the customer or as a third party inspection?
- What are the acceptance criteria?
- Are there special requirements of appearance? Easy-to-clean properties, colourfastness and visibility of repair?
We can be your sparring partner in all of the above and together we lay down the optimal specification for your specific project.
Precise specifications give expected results
The coating company must perform their work according to the specification. If there is no clear specification, they are right to do what they think best. However good practice is not the same everywhere.
Therefore, it is important to include everything in the specification. We typically base it on internationally recognised norms and standards for coating, for instance DS/EN ISO 12944, DS/EN ISO 1461 and NORSOK M-501. By specifying according to standards, the requirements become unambiguous.
Thus, the coating company knows that when you have specified e.g. P3 according to DS/EN ISO 8501-3, the welds must be burnished, must have no welding beads, and all edges must be rounded to a radius of 2 mm etc.
The coating company also knows that when you have specified the paint system A5M.06 according to DS/EN ISO 12944, it requires a base coat with a zinc-rich primer with either epoxy, polyurethane or ethyl silicate as binder in a dry layer thickness of 40-80 µm.
Moreover, 3-4 coats of epoxy or polyurethane should succeed it to a total dry layer thickness of 320 µm.
A good and precise specification ensures that your coating company knows exactly what you expect them to deliver. Thus, your steel construction - regardless of whether it is a wind turbine, a bridge, a tank or something else – is optimally protected against degradation by corrosion.
A good specification based on international standards also ensures that in the case of disputes, nobody will doubt what you required originally.
Impartial and specialised consultancy
FORCE Technology’s specialists and FROSIO
–certified inspectors (NS 476) provide you with impartial and professional sparring on selection of coating as well as requirements for execution and inspection of the coating.
With an unambiguous specification, you get correct and long-lasting protection.
Contact us and let us help you in the right direction.